MYLOTHRITES PLUTO. 49 



distinct from the dai'ker base above the next to the lowest subcostal nervnle ; this 

 belt darkens toward the outer border, especially in slight dusky lleckings along 

 the nervures and down the middle of the interspaces; the latter streaks reach 

 small, round, blackish spots about one-quarter the width of the interspaces, in 

 the middle of the basal two-thirds of their lighter parts. Heer represents them 

 too far from the outer margin of the wing, and as often crowned above with a 

 dark semicircular line, which is not at all indicated in the drawing made for me; 

 these spots are found in all the interspaces below the outermost superior sub- 

 costal nervule, but they are very indistinct and minute above, faint below and only 

 distinct and as large as stated in the three interspaces next above the lowest 

 median nervule. The light belt is two interspaces wide in the upper median 

 interspace, but widens a little above this and is separated from the darker base 

 by a vague and very slightly crenatc line (less crenate than in the representation 

 by Heer), which approaches the outer margin at the nervures and to a slightly 

 greater extent in the lower part of each interspace than in the upper. 



Pierids with so dark a coloring as appears in this fossil are not unknown, 

 particularly in the genera Archonias and Pereute; compare for example the figure 

 given in Doubleday and Hewitson's Genera of Diurnal Lepidoptera, PI. V, fig. 

 2. And that markings of this character are not unknown, compare some species of 

 Ixias, Hebomoia and allied genera; if the colors of Hebomoia Leucippe, as given 

 by Doubleday and Hewitson, were reversed, the resemblance to Pluto would be 

 rather close; and while light spots in a dark border are the rule in this subfamily, 

 dark spots on a light ground are not unknown, and the reversal of tints is a 

 not uncommon occurrence in nearly related Lepidoptera. 



A second fossil, which I have been unable to see or to have redrawn, is given 

 by Heer as probably representing the under surface of the same insect. His re- 

 marks are as follows: 1 



Hierher recline ich auch em Stuck eines Unterfliigels aus der Gratzer Samm- 

 lung, das bei Taf. XIV, Fig. 5 [PI. II, fig. 15], dargestellt ist. Die Hauptadern 

 treten an diesem Flugelstticke alle hervor. Die beiden Mitteladern schliessen ein 

 nicht sehr grosses Mittelfeld ein; ob dieses durch einen Verbinduugsast zwischen 



"Insekt. Tert. CEning, If, 180. 



